[Issue 21109] Wrong result when using sort() on enum arrays
https://issues.dlang.org/show_bug.cgi?id=21109 Iain Buclaw changed: What|Removed |Added Priority|P1 |P2 --
[Issue 21109] Wrong result when using sort() on enum arrays
https://issues.dlang.org/show_bug.cgi?id=21109
Simen Kjaeraas changed:
What|Removed |Added
CC||simen.kja...@gmail.com
--- Comment #7 from Simen Kjaeraas ---
We can reduce this issue down to this code:
struct S {
int[] arr;
}
unittest {
import std.stdio;
foreach (idx; 0 .. 10) {
writeln([S([0])] < [S([0])]);
}
}
I'm not convinced that being able to compare two arrays like this should be
possible at all - the rule that for any T where T.init < T.init does not
compile, [T.init] < [T.init] should not compile seems sensible to me.
If we need it to work, it should definitely do a member-by-member comparison.
Not least, this should be documented.
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[Issue 21109] Wrong result when using sort() on enum arrays
https://issues.dlang.org/show_bug.cgi?id=21109
--- Comment #6 from Andrej Mitrovic ---
(In reply to Boris Carvajal from comment #5)
> There is no 'opCmp' defined for the struct so the runtime just use a memcmp
> for the comparison.
> The code itself calls '__cmp' from core/internal/array/comparison.d (because
> the element are an array '[S(2, [0, 0])]') and there the 3 'static if'
> conditions fail but if you define 'opCmp' the second path is taken.
>
> So the following works:
>
> struct S
> {
> int[] arr;
> int opCmp(ref const S s) const { return arr < s.arr; }
> }
>
> There is a comment on clone.d file that says:
>
> "Essentially, a struct which does not define opCmp is not comparable."
>
> This concise phrase should be on the spec.
Hmm.
In the past the compiler would also do memcmp when a struct didn't define
`opEquals`, but we changed it so it does member-by-member `==` comparison.
I wonder if we can do something similar for opCmp, or if that wouldn't make
sense..
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[Issue 21109] Wrong result when using sort() on enum arrays
https://issues.dlang.org/show_bug.cgi?id=21109
Boris Carvajal changed:
What|Removed |Added
CC||boris...@gmail.com
--- Comment #5 from Boris Carvajal ---
There is no 'opCmp' defined for the struct so the runtime just use a memcmp for
the comparison.
The code itself calls '__cmp' from core/internal/array/comparison.d (because
the element are an array '[S(2, [0, 0])]') and there the 3 'static if'
conditions fail but if you define 'opCmp' the second path is taken.
So the following works:
struct S
{
int[] arr;
int opCmp(ref const S s) const { return arr < s.arr; }
}
There is a comment on clone.d file that says:
"Essentially, a struct which does not define opCmp is not comparable."
This concise phrase should be on the spec.
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[Issue 21109] Wrong result when using sort() on enum arrays
https://issues.dlang.org/show_bug.cgi?id=21109 Andrej Mitrovic changed: What|Removed |Added Summary|Possibly wrong codegen when |Wrong result when using |using enum arrays |sort() on enum arrays --
